Abstract
A trial was carried out to determine the effects of different fertility regimes on the cold tolerance of tall fescue. Tall fescue was grown on soil amended with thermophile sewage sludge compost and chemical fertilizer; soil without amendment was also prepared as the control. After establishing, grass was used for NMR determination. Temperature was lowered in every 5℃-step from 25 to -30℃. T_1s were measured using saturation recovery method. T_2s were measured using CPMG method and solid echo method. There was no change in Arrhenius plot of T_1 in fescue leaves responded to lowering temperature from 25 to 0℃; then a slight increase was observed from -5 to -10℃ for almost treatments. On the contrary, T_2 of fescue leaves gradually increased along with decreasing temperature from 25 to -15℃. Subsequently, a sharp decline in T_2 was observed at temperature ranging from -20 to -30℃ for all treatments. The increase up to 60-70% of T_2 short fraction ratio probably indicates that tissue water began freezing at these temperatures. Results from NMR determination suggested that T_1 was affected by water content (r=0.87); T_1 value of the control was lowest corresponded to the lowest amount of water in the leaves. The supercooling ability was highest for fescue grown on compost-fertilizer blend. Freezing temperature of -18.8℃ in this treatment was approximately 2 to 4℃ lower than the others. It means that fescue grown on compost-fertilizer tolerated cold stress better than fescue grown on other amendments.
